Field of the Invention
In one of its aspects the present invention relates to a radiation source cleaning system, particularly for use in a fluid treatment system. In another of its aspects, the present invention relates to a radiation source module containing the radiation source cleaning system fluid treatment system incorporating a radiation source module.
Description of the Prior Art
Fluid treatment systems are generally known in the art. More particularly, ultraviolet (UV) radiation fluid treatment systems are generally known in the art.
Early treatment systems comprised a fully enclosed chamber design containing one or more radiation (preferably UV) lamps. Certain problems existed with these earlier designs. These problems were manifested particularly when applied to large open flow treatment systems which are typical of larger scale municipal waste water or potable water treatment plants. Thus, these types of reactors had associated with them the following problems:                relatively high capital cost of reactor;        difficult accessibility to submerged reactor and/or wetted equipment (lamps, sleeve cleaners, etc);        difficulties associated with removal of fouling materials from fluid treatment equipment;        relatively low fluid disinfection efficiency, and/or        full redundancy of equipment was required for maintenance of wetted components (sleeves, lamps and the like).        
The shortcomings in conventional closed reactors led to the development of the so-called “open channel” reactors.
For example, U.S. Pat. Nos. 4,482,809, 4,872,980 and 5,006,244 (all in the name of Maarschalkerweerd and all assigned to the assignee of the present invention and hereinafter referred to as the Maarschalkerweerd #1 Patents) all describe gravity fed fluid treatment systems which employ ultraviolet (UV) radiation.
Such systems include an array of UV lamp modules (e.g., frames) which include several UV lamps each of which are mounted within sleeves which extend between and are supported by a pair of legs which are attached to a cross-piece. The so-supported sleeves (containing the UV lamps) are immersed into a fluid to be treated which is then irradiated as required. The amount of radiation to which the fluid is exposed is determined by the proximity of the fluid to the lamps, the output wattage of the lamps and the flow rate of the fluid past the lamps. Typically, one or more UV sensors may be employed to monitor the UV output of the lamps and the fluid level is typically controlled, to some extent, downstream of the treatment device by means of level gates or the like.
The Maarschalkerweerd #1 Patents teach fluid treatment systems which were characterized by improved ability to extract the equipment from a wetted or submerged state without the need for full equipment redundancy. These designs compartmentalized the lamp arrays into rows and/or columns and were characterized by having the top of the reactor open to provide free-surface flow of fluid in a “top open” channel.
The fluid treatment system taught in the Maarschalkerweerd #1 Patents is characterized by having a free-surface flow of fluid (typically the top fluid surface was not purposely controlled or constrained). Thus, the systems would typically follow the behaviour of open channel hydraulics. Since the design of the system inherently comprised a free-surface flow of fluid, there were constraints on the maximum flow each lamp or lamp array could handle before either one or other hydraulically adjoined arrays would be adversely affected by changes in water elevation. At higher flows or significant changes in the flow, the unrestrained or free-surface flow of fluid would be allowed to change the treatment volume and cross-sectional shape of the fluid flow, thereby rendering the reactor relatively ineffective. Provided that the power to each lamp in the array was relatively low, the subsequent fluid flow per lamp would be relatively low. The concept of a fully open channel fluid treatment system would suffice in these lower lamp power and subsequently lower hydraulically loaded treatment systems. The problem here was that, with less powerful lamps, a relatively large number of lamps was required to treat the same volume of fluid flow. Thus, the inherent cost of the system would be unduly large and/or not competitive with the additional features of automatic lamp sleeve cleaning and large fluid volume treatment systems.
This led to the so-called “semi-enclosed” fluid treatment systems.
U.S. Pat. Nos. 5,418,370, 5,539,210 and Re36,896 (all in the name of Maarschalkerweerd and all assigned to the assignee of the present invention and hereinafter referred to as the Maarschalkerweerd #2 Patents) all describe a cleaning system for use with a radiation source (e.g., a UV radiation source). The cleaning system is characterized by having a cleaning chamber on the exterior of the sleeve (e.g., quartz sleeve) of the radiation source (e.g., UV radiation source). The cleaning chamber is configured to receive a cleaning fluid and preferably comprised a sealing element (e.g., an O-ring) at opposed ends thereof. The cleaning system further comprised a motive element configured to move the cleaning chamber between a retracted position and an extended position with respect to the radiation source. The cleaning system described in the Maarschalkerweerd #2 Patents was a significant advance in the art. Specifically, it is believed that the cleaning system described in the Maarschalkerweerd #2 Patent was the first cleaning system for use with a radiation source that combined mechanical cleaning (via the sealing elements or O-rings in the cleaning chamber) with chemical cleaning (via the cleaning fluid in the cleaning chamber). This combined effect was found to be much better to remove fouling materials from the exterior of the radiation source compared to using mechanical cleaning alone (this was the conventional approach prior to the Maarschalkerweerd #2 Patents).
Despite the advance in the art made by the Maarschalkerweerd #2 Patents, there is room for improvement. Specifically, from time to time, it becomes necessary to service the cleaning system, more particularly to replace elements (e.g., O-ring, V-shaped seal and the like) which serve as seals and provide mechanical action to remove fouling materials from the radiation sources. In the cleaning system as described in the Maarschalkerweerd #2 Patents, it becomes necessary to dissemble the radiation source module containing the cleaning system, remove and replace the O-rings described therein and re-assemble everything again. This requires that the module be removed from service for a lengthy period of time requiring redundant equipment (and increased capital costs) or shutting the entire fluid treatment down (thereby negatively affecting the overall efficiency of the fluid treatment system).
Thus, it would be highly desirable to have a cleaning system which maintain the benefits of chemical and mechanical cleaning on the one hand but allow for relatively quick replacement of the sealing element (e.g., O-ring, V-shaped seal and the like). Preferably, this would be done: (i) without requiring removal of the entire cleaning system from the radiation source module, and/or (ii) relatively quickly so that the radiation source module could be returned to service without significant down time.
Thus, it would be highly desirable to have a cleaning system and radiation source module that overcomes the above problems.